SM 25x275 [2xM8] / N42 - magnetic separator

Strengths and weaknesses of NdFeB magnets.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They do not lose strength, even after nearly ten years – the decrease in lifting capacity is only ~1% (based on measurements),
• Neodymium magnets prove to be remarkably resistant to magnetic field loss caused by magnetic disturbances,
• The use of an refined finish of noble metals (nickel, gold, silver) causes the element to present itself better,
• Magnets are characterized by impressive magnetic induction on the surface,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can function (depending on the form) even at a temperature of 230°C or more...
• Possibility of individual forming and optimizing to individual needs,
• Fundamental importance in innovative solutions – they are commonly used in magnetic memories, drive modules, precision medical tools, also complex engineering applications.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

What to avoid - cons of neodymium magnets: weaknesses and usage proposals

• To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution protects the magnet and simultaneously increases its durability.
• NdFeB magnets lose power when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of strength (a factor is the shape and dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• They oxidize in a humid environment. For use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• Limited possibility of creating nuts in the magnet and complex forms - recommended is cover - magnet mounting.
• Potential hazard resulting from small fragments of magnets pose a threat, in case of ingestion, which gains importance in the context of child safety. Additionally, small components of these products can complicate diagnosis medical in case of swallowing.
• With mass production the cost of neodymium magnets is economically unviable,

Detachment force of the magnet in optimal conditions – what it depends on?

The specified lifting capacity concerns the peak performance, obtained under ideal test conditions, specifically:

• using a sheet made of high-permeability steel, serving as a magnetic yoke
• whose thickness reaches at least 10 mm
• with a surface cleaned and smooth
• with total lack of distance (no impurities)
• under axial force direction (90-degree angle)
• in neutral thermal conditions

Practical lifting capacity: influencing factors

Please note that the working load will differ subject to the following factors, starting with the most relevant:

• Gap between surfaces – even a fraction of a millimeter of separation (caused e.g. by varnish or unevenness) diminishes the pulling force, often by half at just 0.5 mm.
• Force direction – declared lifting capacity refers to pulling vertically. When slipping, the magnet exhibits significantly lower power (often approx. 20-30% of maximum force).
• Wall thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field passes through the material instead of converting into lifting capacity.
• Material type – the best choice is pure iron steel. Hardened steels may have worse magnetic properties.
• Plate texture – smooth surfaces guarantee perfect abutment, which improves force. Rough surfaces reduce efficiency.
• Thermal conditions – NdFeB sinters have a sensitivity to temperature. When it is hot they lose power, and at low temperatures they can be stronger (up to a certain limit).

* Holding force was tested on the plate surface of 20 mm thickness, when the force acted perpendicularly, in contrast under parallel forces the holding force is lower. Moreover, even a minimal clearance {between} the magnet’s surface and the plate lowers the holding force.